From 8eb20d1fb0eb3a3b96d5e80e2e2617f893ef6986 Mon Sep 17 00:00:00 2001
From: Siri Hansen <siri@erlang.org>
Date: Thu, 20 Feb 2014 16:45:28 +0100
Subject: Add info about upgrade of core applications

In ref man for appup and in system documentation, design prinsiples,
add a warning related to upgrade when version of erts, kernel, stdlib
or sasl is changed. This will cause an emulator restart where new
version of emulator and core applications will startup together with
old versions of other applications. Care must be taken to avoid
problems due to backwards incompatibility.
---
 lib/sasl/doc/src/appup.xml | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

(limited to 'lib/sasl/doc/src/appup.xml')

diff --git a/lib/sasl/doc/src/appup.xml b/lib/sasl/doc/src/appup.xml
index 85fcbed3ba..95f315d269 100644
--- a/lib/sasl/doc/src/appup.xml
+++ b/lib/sasl/doc/src/appup.xml
@@ -4,7 +4,7 @@
 <fileref>
   <header>
     <copyright>
-      <year>1997</year><year>2013</year>
+      <year>1997</year><year>2014</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -84,6 +84,9 @@
     version identifier must be specified as a binary, e.g.</p>
     <code type="none">&lt;&lt;"2\\.1\\.[0-9]+">></code>
     <p>will match all versions <c>2.1.x</c>, where x is any number.</p>
+    <p>Note that the regular expression must match the complete
+    version string, so the above example will work for for
+    e.g. <c>2.1.1</c>, but not for <c>2.1.1.1</c></p>
   </section>
 
   <section>
@@ -339,7 +342,7 @@ restart_new_emulator
       version of erts, kernel, stdlib and sasl are used when the
       emulator restarts. Only one <c>restart_new_emulator</c>
       instruction is allowed in the relup, and it shall be placed
-      first. <seealso marker="systools#make_relup/3">systools:make_relup3,4</seealso>
+      first. <seealso marker="systools#make_relup/3">systools:make_relup/3,4</seealso>
       will ensure this when the relup is generated. The rest of the
       relup script is executed after the restart as a part of the boot
       script.</p>
@@ -347,11 +350,25 @@ restart_new_emulator
       completed. To programatically find out if the upgrade is
       complete,
       call <seealso marker="release_handler#which_releases/0">
-      release_handler:which_releases</seealso> and check if the
+      release_handler:which_releases/0,1</seealso> and check if the
       expected release has status <c>current</c>.</p>
     <p>The new release must still be made permanent after the upgrade
       is completed. Otherwise, the old emulator is started in case of
       an emulator restart.</p>
+    <warning>
+      <p>As stated above, the <c>restart_new_emulator</c>
+	instruction causes the emulator to be restarted with new
+	versions of <c>erts</c>, <c>kernel</c>, <c>stdlib</c> and
+	<c>sasl</c>. All other applications, however, will at startup
+	be running their old versions in this new emulator. In most
+	cases this is no problem, but every now and then there will be
+	incompatible changes to the core applications which may cause
+	trouble in this setting. Such incompatible changes (when
+	functions are removed) are normally preceded by a deprecation
+	over two major releases. To make sure your application is not
+	crashed by an incompatible change, always remove any call to
+	deprecated functions as soon as possible.</p>
+    </warning>
     <pre>
 restart_emulator
     </pre>
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